20261022-0420-key-box-rs485-analog-inputs Key Box 36: RS-485, eight configurable analog inputs and board monitoring
- status: completed
- priority: P1
- owner: claude/key-box-aio-0420
- createdAt: 2026-10-22 04:20
Description
章节标题：“Description”Key Box 36 has 18 spare AMPSEAL pins (J2 29-32 / 34-35, J3 / J4 30-35) and one spare GPIO (IO8). The owner asked for RS-485 and software-configurable 0-190 Ohm / 4-20 mA inputs without an external ADC, plus board temperature, current and rail monitoring (2026-10-22: "可以，按这个来做 1，用非隔离 2，用8路软件可配置 3，应该不需要吧" = non-isolated RS-485, 8 configurable channels, no 24 V loop boost).
Acceptance:
- RS-485 (THVD1406, auto-direction, non-isolated) on UART0 at J2 29 A / 30 B / 31 TERM / 32 shield / 34 GND; 120 R enabled by a harness bridge; console moves to USB Serial/JTAG.
- AIN1-AIN8 on J3 / J4 30-33, each 0-190 Ohm (1k pull-up) or 4-20 mA (100 R shunt switched by a FET from a 74HC595 latched on IO8), read by TIC12400 IN11-IN14 in ADC mode, ratiometric to +5V on IN15; J3 / J4 34 sensor ground and 35 loop supply, PTC protected; all channels start in Ohm mode while DO_EN is low.
- Box current (10 mR + INA186), 2 NTCs and the 3.3 V rail on U9 IN11-IN14.
- Schematic ERC 0; PCB DRC 0 unconnected / clearance / short; spec, design appendix, guide and the key-box README follow.
ActiveForm
章节标题：“ActiveForm”Adding RS-485, analog inputs and monitoring to Key Box 36
Dependencies
章节标题：“Dependencies”- blocked by: (none)
- blocks: (none)
Notes
章节标题：“Notes”Plan: docs/plan/20261022-0420-key-box-rs485-analog-inputs.md
- complete: RS-485, AIN, boost, HSO, monitoring, 5 A, WROOM-1-N8; DRC 0